THIS invention relates to cassettes for photographic film material mounted on a spool.
Cassettes of this type, which find particular use in 35 mm cameras, are light tight so that they can be placed into and removed from a camera in the light. The cassette has a pair of lips through which the leading edge of the roll of film material protrudes. This leading edge is pulled out and fastened on to the take-up spool of the camera when loading the camera. It is important that light is not able to enter into the cassette through the lips of the cassette and in order to prevent the ingress of light the lips are usually lined internally with velvet or other such material. However the velvet or other such material which can be used prevent the ingress of light into the cassette is expensive and difficult to secure firmly in place within the lips of the cassette. Further dust or dirt particles are able to become entrapped in the velvet and these particles when so trapped will scratch any film material which is drawn over them. This happens particularly if the cassette is reloaded with film and re-used.
There is described in U.S. Pat. No. 3,128,058 a cassette which has a pair of lips which extend inwardly into the cassette to form a light labyrinth which traps the light and thus obviates the need to use a velvet light seal. However in this proposed cassette the labyrinth contains a number of steps and baffles which are required to prevent the ingress of light.